In this respect, another approach, less amenable to fine-tuning criticisms, has recently been explored [1]}, [2]}, [3]}. Considering changes in the pressure of the early Universe plasma, enhanced gravitational collapse occurs because \(\delta _c\)  decreases with the slight softening of the equation of state (EOS) parameter \(w\) . Therefore, this approach does not require the presence of a large peak, but simply a featureless power spectrum with an amplitude that has not to be so largeThis strictly holds for Gaussian fluctuations. For the effects of non-Gaussianities, see e.g. Refs. [4]}, [5]}, [6]}, [7]}, [8]}, [9]}, [10]} .. A very appealing aspect of this model is that it might explain the nature of CDM and the LIGO-Virgo results with only elements of the SM of particle physics. For example, the Higgs field playing the role of the inflaton can produce a (near) plateau in the primordial power spectrum by slowing down after crossing a near-inflection point related to the critical value of the running of its self-coupling and non-minimal coupling to gravity [11]}. Then, SM particles becoming non-relativistic produce sudden drops in the EOS that cause the mass function to show peaks around \(10^{-6},\,2,\,60\)  and \(10^6\, M_\odot \) . Such peaks are a key prediction of the model.
